Press stand for hydrostatic extrusion of a billet



Oct. 6, 1970 3,531,965

PRESS STAND FOR HYDROSTATIC EXTRUSION OF A BILLET Filed Sept. 30. 1968 4 Sheets-Sheet 1 INVENTOR. JA N NI L SSON Oct. 6, 1970 J. NILSSON 3,531,965

PRESS STAND FOR HYDROSTATIC EXTRUSION OF A BILLET Filed Sept. 50. 1968 4 Sheets-Sheet z MENTOR. JAN NILSSON BY gmkgfg i 8 Oct. 6, 1970 J. NILSSON 3,531,965

PRESS swan FOR HYDROSTATIC EXTRUSION OF A BILLET Filed Sept. 30. 1968 r 4 Sheets-Sheet s Fig. 4

INYENTOR. JAN N L55 0 N Oct. 6, 1970 & s 0 3,531,965

PRESS STAND 'FORHYDROSTATIC EXTRUSION OF 'A BILLET Filed Sept. 30. 1968 4 Sheets-Sheet 4.

Fig. 6

JNVENIOR. JA N N I L6 SON United States Patent O 3,531,965 PRESS STAND FOR HYDROSTATIC EXTRUSION OF A BILLET Jan Nilsson, Robertsfors, Sweden, assignor to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden Filed Sept. 30, 1968, Ser. No. 763,793

Claims priority, application Sweden, Oct. 6, 1967,

13,689/67 Int. Cl. 1321c 23/08 US. CI. 72-60 Claims ABSTRACT OF THE DISCLOSURE A press for hydrostatic extrusion has a stand on which a die is mounted. A pressure chamber containing pressure fluid is mounted on the stand for movement towards and away from the die. A billet holder composed of a piston having a spring-pressed one-way valve therein is mounted for movement in the pressure chamber, the side facing the die being shaped to center the end of a billet held between it and the die. The pressure chamber is withdrawn from the die and a billet is positioned between it and the die by inserting mechanism. The pressure chamber is then advanced to engage over the rear end of the billet and the billet holder is moved forwards until it holds the billet between itself and the die. A piston is then forced into the rear end of the pressure cylinder to extrude the billet, the pressure fluid passing through the valve in the billet holder after its pressure becomes great enough to overcome the resistance of the spring so that the fluid can press directly on the billet.

BACKGROUND OF THE INVENTION ,(1) Field of the invention The present invention relates to a press, preferably horizontal, for hydrostatic extrusion of a billet enclosed in a high pressure chamber.

(2) The prior art Presses for this purpose have previously usually been made with a vertical pressure chamber where, without the help of complicated holding members, a billet can be positioned against the inlet opening of a die and obtain the necessary sealing between die and billet so that a pressure necessary for the extrusion process can be built up. Press stands having horizontal pressure chambers, which are more advantageous for large scale production, must be provided with means to hold the billet in the correct position in the pressure chamber and press it against the die so that sealing is obtained between the billet and the die. Press stands are known in which the piston which generates the pressure in the pressure chamber exerts a certain pressure on the billet so that it is held against the die at the start of the extrusion process. This type of press can operate horizontally. However, these presses have two high pressure chambers movable against each other and a common piston means movable in both the chambers and a pressure medium connection between the two chambers arranged inside the movable piston member. The press stand is then long and thus has poor stability. Furthermore, the channel in the piston means is an undesirable weakening of this.

SUMMARY OF THE INVENTION The press according to the invention comprises a liquid-filled high pressure chamber, a die having at least one extrusion opening, a piston which, when pushed into the pressure chamber, generates the necessary hydrostatic ice pressure to extrude a bilet inserted in the chamber, and a billet holder to hold the billet against the die before the start of the extrusion process.

It is essentially characterized in that the billet holder consists of a movable piston dividing the pressure chamber into two spaces, which piston on the side facing the billet is shaped to centre and clamp the billet and which has at least one overflow valve which, at a certain pressure difference between the sides of the piston, permits liquid to flow from the space between the pressure-generating piston and the billet holder to the space between the billet holder and the die. The side of the billet holder facing the billet is suitably shaped as a cone. The high pressure chamber of the press is arranged for axial displacement away from a press table acting as support for the die. The press may also include an inserting mechanism for the billet which inserts a billet between the pressure chamber and the die and keeps the billet in position while the pressure chamber is moved over the billet until the billet holder arranged in the pressure chamber, by exerting a pressure on the billet, fixes this against the die. At the side of the pressure chamber where the pressure-generating piston is inserted, a space is arranged through which pressure medium can be introduced in the pressure chamber so that the billet holder is displaced towards the billet and holds it by pressing it against the die.

By means of the invention a press is obtained for hydrostatic extrusion which can be used for large scale production. It is short in construction and can with advantage be provided with automatically operating insert ing mechanisms of simple types for inserting the billets.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described more fully with reference to the accompanying drawings. FIG. 1 shows a section through a billet holder and the adjacent part of the high pressure chamber. FIGS. 2-8 show longitudinal sections through a press showing the positions of the parts in relation to each other at different moments during a working cycle. FIG. 9 shows a section taken along the line A-A in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIEMENT In the drawings 1 designates a billet holder freely movable in axial direction in the pressure cylinder 2 of a high pressure chamber and dividing the pressure chamber into two spaces 3 and 4. For the extrusion a pressure-generating piston 5 is inserted into the space 3 and the billet 6 is in the space 4. The billet holder 1 is shaped as a piston with a seal 7 and a conical end surface 8 on its side facing the space 4. It is provided with overflow channels 9 and 10, a valve 11 with a valve cone 12 influenced by a spring 13 and an overflow channel 14 which prevents the pressure between the cone 8 and a billet 6 from exceeding the pressure in the space 4.

The high pressure cylinder 2 is horizontally arranged in a press stand having a vertical press table 15 and an end piece 16 which is held together by four set bolts 17.'The press table 15 has a support 18 for a press die 19. An operating cylinder 20 is arranged in the end piece 16 with a diflerential piston 21 to operate the pressuregenerating piston 5. 50 designates a lid for the cylinder 20. The spaces 23 and 24 on either side of the piston 21 are in communication with a pressurized oil source, not shown, by means of conduits 25 and 26. An operating cylinder 22 is also arranged in the end piece 16 to operate the high pressure cylinder 2. The operating cylinders comprise a piston 27 which, with the rod 28, is joined to the high-pressure chamber 2. The spaces 29 and 30 on either side of the piston 27 are in connection with a pressurized oil source, not shown, by means of conduits 31 and 32. The high pressure cylinder 2 is suspended in two brackets 33 supported by two axially slidable sleeves 34 arranged on the upper bolts 17. At one end of the high pressure cylinder 2 is a seal 35 which seals between the cylinder 2 and the die 19. At the other end are two seals 36 and 37 which seal against the pressure-generating piston 5. Between the seals 36 and 37 is an annular space 38 which is in communication with a pressure medium source through the conduit 39. The seal 37 is with advantage arranged in a separate sleeve which at its connection to the high pressure cylinder 2 forms the annular space 38.

At one end of the press stand is a mechanism 59 to insert the billet 6 and the die 19 in the correct position in relation to the cylinder 2. This consists of a gripping means 40 which, through the piston rod 41, is connected to the piston 42 in the operating cylinder 43. The spaces 44 and 45 on either side of the piston 42 are in communication with operating valves and a pressurized oil source, not shown, by means of the conduits 46 and 47. 48 is an extruded product, 49 the remnants of a billet; and 51 a cross-cutting saw.

The method of operation of the press is described in the following with the help of the series of figures showing a number of different steps in an operating cycle. 1n FIG. 2 the piston and cylinder 2 are in their left-hand end positions and a billet 6 and die 19 held, in the holder 40 in the insertion mechanism 59, have been moved by theoperating piston 42 to a position opposite the space 4 in the cylinder 2. The cylinder 2 is displaced by the operating cylinders 22 to the right to the position shown in FIG. 3. In this figure the billet 6 is partly inside the space 4 in the cylinder 2 and the piston 5 is in such a position in relation to the cylinder that sealing is obtained between the piston 5 and the cylinder 2 by the Sealing ring 37 and there is a free passage for the introduction of pressure medium into the space 3 through the conduit 39 and the annular space 38. The cylinder 2 is held in this position and pressure medium is supplied to the space 3. When the pressure rises in the space 3 the billet holder 1 is displaced to the right and its conical surface 8 gradually comes into contact with the billet 6 and presses this against the die 19 and the die against the support 18 on the press table with a force which is limited by the opening pressure of the valve 11. The billet and the die are now held by the pressure and the holder 40 is pulled away by the operating cylinder 43 by pressure medium being supplied to the space 44. The position in FIG. 4 has now been reached. Due to the constant supply of oil through the conduit 39 and the space 38 to the space 3, the cylinder 2 and piston 5 are displaced simultaneously and with the same speed to the right until the movement of the cylinder 2 is checked by contact with the support 18. Due to the oil supply an oil flow is obtained through the valve 11 into the space 4 so that this is filled with oil when the seal 35 slides in over the die 19 so that sealing is obtained between the cylinder and the die.

The position according to FIG. 5 has now been reached. The pressure piston 5 is moved further to the right and passes the high pressure seal 38 as shown in FIG. 6, after which the hydrostatic pressure required for the extrusion is built up and the extrusion process commences. When the extrusion commences the billet is held in the correct position by the liquid pressure. It is of no importance that the holder 1 now releases the billet. FIG. 7 shows the position at the end of the extrusion. The piston 5 and cylinder 2 are now moved simultaneously back to their left-hand end positions and the die 19 with the remnants of a billet is displaced somewhat to the left by means not shown. The position according to FIG. 8 has now been obtained. A cross-cutting saw 51 is now moved forward and cuts the rod 48 close to the die 19. The remnants of the billet 49 are removed from the die 19 after which the die and a new billet are inserted into the inserting mechanism 59 and a new operating cycle can be started.

The invention is of course not limited to the shown embodiment. Several variations and modifications are feasible within the scope of the following claims.

What is claimed is:

1. Press for hydrostatic extrusion comprising a press stand, a cylindrical high pressure chamber mounted on said stand and filled with liquid, a die mounted on said stand and having at least one extrusion opening, a piston which, when pushed into the pressure chamber, generates the necessary hydrostatic pressure to extrude a billet inserted in the chamber, and a billet holder, in which the billet holder comprises a second movable piston dividing the pressure chamber into two spaces, which second piston on the side facing the billet is shaped to center and clamp the billet and which has at least one overflow valve which, at a certain pressure difference between the sides of the second piston, permits liquid to flow from the space between the pressure-generating piston and the billet holder to the space between the billet holder and the die.

2. Press according to claim 1, in which the side of the billet holder facing the billet is shaped as a cone to center and clamp the billet.

3. Press according to claim 1, in which the pressure chamber is arranged for axial displacement away from the die.

4. Press according to claim 3, Which comprises an inserting mechanism for the billet which inserts a billet between the pressure chamber and the die and keeps the billet in position while the pressure chamber is moved over until the billet holder arranged in the pressure chamber, by exerting a pressure on the billet, fixes the billet against the die.

5. Press according to claim 1 in which, at the side of the pressure chamber where the pressure-generating piston is inserted, a channel is arranged through which pressure medium can be introduced in the prwsure chamber when billets are inserted, so that the billet holder is displaced towards the billet and holds the billet by pressing it against the die.

References Cited UNITED STATES PATENTS RICHARD J. HERBST, Primary Examiner 

